Features:

Open source Linux (OpenWrt) inside
Low power consumption
Compatible with Arduino IDE 1.5.4 or later, user can program, debug or upload sketch to Arduino board via Arduino IDE.
Managed by Web GUI, SSH via LAN or WiFi
Software upgradable via network
Built-in web server
Support internet connection via LAN port, WiFi or 3G dongle
Support USB flash to provide storage for Arduino projects
Failsafe design provides robustly system
Compatible with Arduino Leonardo, Uno , Duemilanove, Diecimila, Mega

Product Description:

Processor: 400MHz, 24K MIPS
Flash: 16MBytes
RAM: 64MBytes
Power Input: 9v ~ 23v via Arduino VIN pin
1 x 10M/100M RJ45 connector
150M WiFi 802.11 b/g/n
External Antenna via I-Pex connector
2 x USB 2.0 host connectors, used for USB storage or 3G connection
1 x micro SD card slot
1 x Reset button
Compatible with 3.3v or 5v I/O Arduino.
Package Included:

Yun Shield v2.4*1